Modern transceivers in wireless communication standards (e.g., cellular, connectivity, etc.) implement transmitters with architecture belonging to a restricted number of alternative classes. As one example, communication standards with constant amplitude modulation schemes (e.g., plain vanilla GSM (Global System for Mobile communications)) use mainly the sigma-delta PLL (Phase Locked Loop) loop architecture, but also the straightforward Cartesian architecture (also referred to as I&Q (in-phase (I) and quadrature (Q)) architecture). As another example, communication standards requiring higher transmission data rates and, consequently, a more efficient usage of the frequency spectrum (e.g., OFDM (Orthogonal Frequency Division Multiplexing), rely on modulation schemes with both amplitude and phase modulation. In the latter cases, the most used transmitter architectures are the Cartesian (I&Q) and the so-called polar modulation architecture.
In all these communication standards, the baseband signal to be transmitted is complex in nature—that is, it is composed of a sequence of samples with a real and an imaginary part. Put simply, each sample of the signal to be transmitted is for all purposes equivalent to the coordinates of a point in a two dimensional plane. The alternative transmitter architectures correspond, then, to alternative ways of expressing these same coordinates.